A communication system using radio frequency identification (RFID), i.e., an RFID system, is known as a wireless communication technology. This communication system performs, for example, a communication system between a contactless IC card and a reader writer. In this communication system, it is possible to classify communications into two types depending on a communication direction, i.e., communication from the reader writer to the card and communication from the card to the reader writer. In both communication directions, the reader writer constantly oscillates a carrier frequency, and the card performs transmission processing (response processing) as well as receiving processing, on the basis of electric power obtained from this carrier frequency.
In addition, near field communication (NFC) is known as a communication standard of wireless communication. The NFC is a near-field wireless communication technology approved as an international standard, and has been spreading mainly in Asian countries for fields such as a traffic system, charging, and authorization. In recent years, in particular, application to, for example, smartphones and wearable devices has been expected, and downsizing of components to realize functions has been expected. Among components, an antenna is a component that occupies a large area, and technologies that realize downsizing of the antenna have been receiving attention.